Important notes

• On circuit diagrams, plugs are displayed as viewed from the back side, the solder side. Chips are displayed as viewed from above; also, see the small semicircular cut for finding the correct orientation. When in doubt, see the corresponding description on the legend page.

Construction

You need the following parts to build this cable:

• One solderable 6-pin male DIN plug (Commodore serial plug)

• One solderable 25-pin male plug (PC parallel plug)

• Three 1 kOhm resistors

• One 7406 inverter IC

• A shielded 3-wire or unshielded 4-wire cable of, preferably, at most 2 meters

Step 1. Solder one end of the cable onto the DIN plug.

Step 2. Solder the other end of the cable onto the parallel plug. You should have the following connections:

   DIN plug   
 Parallel plug 

    2, GND     
   25, GND     

    4, CLK     
    8, D6      

    5, DATA    
    9, D7      

Step 3. Build the inverter bridges, using the inverter IC. You should have the following connections:

   DIN plug   
  Inverter IC  
  Inverter IC  
 Parallel plug 

    3, ATN     
  2, Output 1  
  1, Input 1   
    5, D3      

    4, CLK     
  4, Output 2  
  3, Input 2   
    6, D4      

    5, DATA    
  6, Output 3  
  5, Input 3   
    7, D5      

This is equivalent with three inverters whose outputs are pointing towards the pins in the left column of the table and their inputs to the ones on the right.

To make soldering on the IC easier, you may want to slightly melt the plastic on the inner side of the case of parallel port plug and carefully embed the IC into it.

Step 4. Supply power for the inverter IC, by connecting it to the parallel port. You should have the following connections:

  Inverter IC  
 Parallel plug 

    7, GND     
   25, GND     

   14, +5V     
   14, +5V     

Step 5. Place the pull up resistors. You should have the following connections:

   DIN plug   
 Parallel plug 

    3, ATN     
   14, +5V     

    4, CLK     
   14, +5V     

    5, DATA    
   14, +5V     

There must be a resistor on each connection but you shouldn't directly connect the pins of the DIN plug together.

Circuit diagram

The numbers besides the inverters show the suggested pin numbers of the inverter IC. You don't have to exactly follow these pin numbers though as the IC has six independent inverters which are all equivalent.

You can find the description of all parts used on the diagrams at the legend page.

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